Question

After $2$ hours the amount of a certain radioactive substances reduces of the original amount (the decay process follows first-order kinetics). The half-life of the radioactive substances is :

• A. $15$ min.
• B. $30$ min.
• C. $45$ min.
• D. $60$ min.

Answer 1

The correct option is B $30$ min.

$\frac{1}{2^n}=\frac{1}{16}\Rightarrow n$ ,number of half-lives $=4=2$ hrs, half-life $=30$ min.